PCB baking instructions before PCBA processing

Friends who are engaged in the PCBA industry know that copper-clad laminates are made by pasting a piece of copper foil on an insulating material and then baking it dry. If you look carefully, you will see that there will be shrinkage during the drying process, and stress will be generated in all directions. This is the source of the stress. Secondly, the purpose of drying the board before drilling is actually mainly to dehumidify. The purpose of drying the board before drilling the PCB is to Remove moisture from the board and reduce internal stress; there is also a printed solder mask after lamination, including characters, etc., which need to be baked. There is also a process of baking the plate before shipment and packaging, also to remove moisture. The baked plate has a relatively large improvement in warpage.

The baking mentioned earlier can eliminate the internal stress of the PCB board, which stabilizes the size of the PCB. Its most significant advantage is that it can dry out the moisture in the pad after baking, enhance the welding effect, and reduce the rate of false soldering and repairs. However, baking will cause a change in the color of the PCB board, which will affect its appearance.

Usually, the baking temperature is 100-120°C, and the baking time is about 2 hours. Do not bake for too long! If it is exposed to the air, it needs to be used up within a day, otherwise oxidation will easily occur. Of course, this is not absolute. It also depends on the production capacity of the supplier. Some OSPs have a longer shelf life.

1. If the PCB is sealed and unpacked for more than 5 days within 2 months of the manufacturing date, please bake it at 120 ±5℃ for 1 hour.

2. If the PCB is more than 2 months old from the manufacturing date, please bake it at 120 ±5℃ for 1 hour before going online.

3. If the PCB is 2 to 6 months older than the manufacturing date, please bake it at 120 ±5℃ for 2 hours before going online.

4. If the PCB is 6 months to 1 year older than the manufacturing date, please bake it at 120 ±5℃ for 4 hours before going online.

5. The baked PCB must be used within 5 days (put into IR REFLOW). After use, it needs to be baked for another 1 hour before it can be used online.

6. If the PCB is more than 1 year old from the manufacturing date, please bake it at 120 ±5℃ for 4 hours before going online, and then send it to the PCB factory for re-tin spraying before going online.

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